The present invention relates to window coverings, and more specifically to blinds which are used to control the amount of light coming through a window. Such blinds are available in various widths. However, a very popular size is one called a mini-blind which has slats which are approximately 1 inch in width. The invention as described herein has been applied to a mini-blind. However, the concepts discussed herein are applicable to other kinds of blinds.
Most blinds which are currently available lifting cords which are used to raise and lower the blind to desired levels, depending upon the amount of light which is to be admitted. The raising and lowering of the blind is achieved by attachment of the lifting cords to a bottom rail so that the slats stack upon one another as the bottom rail is raised. Similarly, as the bottom rail is lowered, the slats are separated by a ladder cord. Typically, each of the slats of the blind has a plurality of openings, one opening for each lifting cord. The openings are generally centrally disposed so that a single lifting cord will extend through the openings of several slats to the bottom rail. A typical arrangement is shown in U.S. Pat. No. 4,567,930, assigned to the assignee of the present invention.
One of the drawbacks of providing a single lifting cord at a particular lifting location is the inability to completely block light that passes through a window. This difficulty arises from the fact that the centrally disposed lifting cord interferes with slat-to-slat contact which would create a "room darkening" blind. While the interference is relatively minor, because small diameter cords are generally used, the cumulative effect of the series of thin horizontal openings between slats created by the interference of the lifting cord makes a significant difference in efforts to create a room darkening blind.
Therefore, it is an object of the present invention to provide a blind which substantially improves the blockage of light therethrough.
It is another object of the invention to provide a blind with slats which do not have holes drilled therethrough.
A further object of the invention is to provide a blind in which the slats thereof may be raised, lowered and adjusted angularly with ease and efficiency.
Yet another object of the invention is to provide a mini-blind in which the slats can be easily replaced without completely disassembling the blind.
Still another object of the invention is to provide a blind in which the complexity and number of parts used to achieve various adjustments of the blind are minimized.
These and other objects of the invention are achieved with a blind in which a plurality of slats are suspended from a headrail to form a vertically disposed array. Raising and lowering of the slats is achieved with a plurality of lifting cords, two cords for each lifting location. The lifting cords for each location extend along the outer edge of the array and, with respect to at least one lifting location, the slats have notches in which the vertical portions of a ladder cord ride. The engagement between the notches and the ladder cords prevent lateral movement of the slats out of alignment. The blind of the present invention also has a unique arrangement of components which are used to actuate raising and lowering, as well as angular adjustment of the slats.